Machine for applying helical fins to cylindrical bodies by means including ironing tools



E. s. LEA 2, MACHINE FOR APPLYING HELICAL. FINS TO CYLINDRICAL BODIES BYMEANS INCLUDING IRONING TOOLS 4 Sheets-Sheet 1 Feb. 28, 19 50 OriginalFiled March- 21, 1942 .ZNVE'NTQR Edward/5. [fa

17. TOR/V153 Feb. 28, 1950 E. s. LEA 2,498,813 W MACHINE FOR APPLYINGHELICAL FINS TO CYLINDRICAL BODIES BY MEANS INCLUDING IRONING TOOLSOriginal Filed March 21, 1942 4 Sheets-Sheet 2 Willi INVHVFQK Edward 5.[d

FY mm;

WFI'ORNEY 2,498,813 NS T0 CYLINICAL Feb. 28, 1950 E. s; LEA

MACHINE FOR APPLYING HELICAL FI BODIES BY MEANS INCLUDING IRONING T00Original Filed March 21, 1942 4 Shets-Sheet 3 Feb. 28, 1950 E s LEA2,498,813

MACHINE FOR APPLYING HEI JICAL FINS TO CYLINDRICAL BODIES BY MEANSINCLUDING IRONING TOOLS- Original Filed March 21, 1942 4 Sheets-Sheet 4[WE/V705 Edwdm/S'. [Pd

Patented F eb. 28, 1950 UNITED STATES PATENT OFFICE MACHINE FOR APPLYINGHELICAL FIN S T0 CY-IiIlSTZDRIGAL BODIES BY MEANS INCLUD- ING IRONINGTQOLS Edward .S. Lea, Morrisville, Pa., assignor to Buensod-Stacey,Incorporated, New York, N. Y., a corporation of Delaware 4'Claims. 1

This invention relates to an apparatus for applying upstanding helicalfins to cylindrical bodies, and is a division of my copendingapplication S. N. 435,728, filed March 21, 1.942, issued March 19, 1946,as Patent No. 2,396,795. Since it has been especially devised for use informing heat radiating fins upon aircraft engine cylinders and the like,the invention will be described with particular reference to its utilityin such an op eration.

The principal object of the invention is to provide a machine fordrawing a preformed helical fin which has been fitted to a cylindricalbody until its inner edge tightly engages the outer surface of that'body, so that it may be bonded in place, and of mechanically workingthe fin after it has been softened and warped by the heat of the bondingoperation for the dual. purpose of hardening it sufiiciently and ofstraightening it so that its convolutions define a series of unitorm aircooling passages.

It-is a furtherobject of the invention to provide a; machine of theforegoing kind which is of simple design and rugged construction-andwhich lends itself to operation by an unskilled mechanic to carry outthe several steps of the method disclosed and claimed in the parentapplication at high speed, thus permitting that method to be put intopractice at minimum expense,

The foregoing and other objects .of the invention, as well as itsvarious features, will be more fully understood from the tollowingdescription in the light of the accompanying drawings,

which:

Figure 1 is an elevational view, partly in section, of a barrel of astandard airplane engine cylinder having :an outer cylindrical surfaceadapted to receive separately formedcooling Fig. 2 is an elevationalview of a preformed helical fin which is adapted tobe applied tocylinder barrel of Fig. 1 by the method of the present invention; I

Fig. 3 is an jelevational view of a cylinder having the fin of Fig. '2fitted :over its barrel, with its leading end secured toone end of thecylinder, this view illustrating the fin at an intermediate stage of itsapplication to the cylinder;

Fig. 4 is a plan view. partly in section, of a fragment of .a machineembodying the principles of the invention and designed to carry outseveral of the steps of the method, and illustrates that method atanother one of its intermediate stages;

Rig. .5 is a sectional view of a fragment of the cylinder barrel afterfinshave. been applied to surface, and after those fins have beenfinally secured in place.

Fig. 6 is a sectional view of a clamping member which is used to securethe trailing end of the fin in fixed relation to the cylinder barrel atthe completion of one of the steps of the method;

Fig. 7 is afront view of the clamp of Fig.6;

Fig. 8 is a sectional view taken on the line -8--8 of Fig. 4;

Fig. 9 is a sectional view of a portion of the machine of Fig. 4;

Figs. 10 and 11 are views illustrating the details of certain portionsof the machine of Figs. 4 and 8;

Fig. 12 is a sectional view taken substantially along the plane of theline "|2-'I2 of Fig. 4;

Fig. 13 is a sectional view of a fragment of a cylinder barrel with acooling fin partially applied to its surface, the view illustrating themethod of the invention at one of its intermediate steps;

Fig. 14 is an end view of a portion of the machine of Fig. 4 as viewedfrom the left end thereof;

Fig. 15 is a plan view, partly in section, of a fragment of thestructure of Fig. 14; and

Figs. 16 and 1'! illustrate one way in which the convolutions of a finapplied by the method of the invention may be held in spaced relationwhile they are being soldered to the barrel.

In the drawings, and referring to Fig. '1, numeral l2 identifies aflanged steel barrel having a flange l3 near one of its ends by whichthe barrel may be secured to the crankcase of an engine, an enlargedshoulder I4 near its other end which will subsequently be threaded toreceive a conventional cylinder head, and an intervening cylindricalsurface l5 of lesser diameter than either the flange or the shoulder. Itwill be assumed for the purpose of description that a helical fin ofcopper is to be applied to this barrel in place of the usual integrallyformed steel heat radiating fins. In accordance with the method of theparent application, a flat strip 16 of copper is first rolled to form ahelix (Fig. 2) having an inside diameter 1 such as to permit thatelement to :be passed endwise over enlarged shoulder 14 of the barreland be brought to rest on thesmaller diametered surface 15. At thisstage of the operation the helical strip will rest loosely upon thebarrel with its convolutions touching one another as is shown in Fig. 3.Preliminary to the drawing out step of the method, the leading end ofthe helix is mechanically fixed to the barrel in any suitable way. Thismay conveniently be done by inserting the hook ll, whichhas been formedat the end of the strip for that purpose, in a slot 18 of a clamp N3;the clamp preferably comprising a part of a driving rin which hastheretofore been'secured on the end of the barrel by set-screw 24. Whenthis has been done, the barrel is fitted to a stub arbor 2!! with thedriving ring disposed adjacent face plate 22. The arbor, face plate, andcertain other elements hereinafter considered, may be parts of anystandard screwcutting lathe the construction and operation of which issufficiently well known not to require description and illustrationhere. At this point, the leading end of strip I6, immediately adjacentclamp i9, is engaged between a pair of tools 25, 26, (see Figs. 4, 8 and13) which are mounted on a frame 21 secured by screws 28 to the crossslide of the lathe so that they may be advanced toward and withdrawnfrom the cylinder barrel at appropriate times. One of the tools, 25, ispreferably secured to an arm 29 which is mounted to swing about pivotpin 30 (see Fig. 4) and a spring 3| serves to urge this tool inwardlywhereby to squeeze the strip between its inner face and that of thefixed tool 26. The pressure which must be applied to the strip by thetools will depend upon the size and thickness of the strip, and upon theextent to which the diameter of the helix must be reduced. In theillustrative case it has been found that the tools should actuallydeform the surfaces of a copper strip. Thus, when the tools have beenadvanced toward the barrel, and the leading end of the strip it has beendisposed between them, the tension of spring 3i may be adjusted by screw32 whereby to squeeze the strip to a desired degree; and the screw maythen be locked in its adjusted position by locknut 33.

The preliminary set-up for the drawing-out step of the method is nowcomplete; and the relative positions which the barrel, strip and ironingtools occupy at the beginning of that step are shown in full lines inFig. 4. Upon the starting up of the machine, a driving pin 34 carried bythe face plate engages cross flange 35 of the driving ring, therebyrotating barrel I! about its own axis and drawing strip is between theironing tools. Simultaneously, the frame 21, and the tools which itcarries, are advanced lengthwise of the barrel by automatic feed screw36 at a uniform rate which is set by the relative speeds of the arbor 2iand of the feed screw. This action therefore serves to locate theconvolutions of the strip at regularly spaced intervals alon surface i5,and at the same time to draw out the strip progressively until its inneredge tightly engages the barrel.

The drawing out of the helical strip to reduce its inside diameter tothat of the outside of the barrel may have three separate components.First, there is the normal reduction in diameter which is occasioned bythe stretching of the helix, that is to say, by the increase in spacingbetween its convolutions from the touching condition which existed whenthe helix was applied to the barrel to that existing when the fin isproperly located at spaced intervals along surface l5. Next, thetightening of the helix as it is twisted about its own axis, much as aspring is wound, causes some reduction of its internal diameter. Incertain Cases the drawing-out step may be limited to these two phases.If, for example, the helix has an initial inside diameter d which issubstantially equal to the outside diameter of the surface over whichthe fin is to be applied, then its reduction in the foregoing manner maybe entirely adequate to cause the inner edge of the fin tightly toengage the surface. Where, however, the helix must be passed over anyconsiderable enlargement at the end of the barrel, then the drawing-outstep will include a further component, namely, an actual drawing andthinning of the outer edge of the strip as it is progressively squeezedbetween the irons. This action produces a lengthenin of the outer edgeof the strip, and the helix immediately adjusts itself to this newcondition by contracting until its inner edge engages the surface of thebarrel in the desired way. In the case under discussion the diameter ofthe shoulder M was one-quarter of an inch greater than that of thesurface I5, while in another instance the difference amounted to as muchas fiveeighths of an inch. In both cases the fin was drawn sufficientlyto make its inner edge tightly hug the smaller diametered cylindricalsurface of the barrel. Whatever the character of the action may be, itresults in an actual reduction of the diameter of the helix which is ofsuch extent as to cause the inner edge of the strip [6 tightly to engagethe surface of the barrel in the desired way. For purposes ofdescription and claiming,

this action will .be referred to as a drawing-out of the fin.

The drawing operation proceeds in the foregoing manner until the ironingtools reach the position shown in dotted lines in Fig. 4, at which timethe machine is brought to a stop. At this point, and while the majorportion of the strip is still held in its tightened condition by itsengagement with the tools 25, 26, the hook 38 at its trailing end isinserted in a slot 39 of a clamp 40 (see Fig. 6) the clamp is fittedover flange I3 of the barrel and is advanced manually along that flangein such a way as to draw the trailing end of the strip tightly to thebarrel; and the trailing end is then secured in fixed relation to thebarrel by turning down a set-screw 43 of the clamp. In many cases thiscompletes the drawing-out step, and the tools may be backed away fromthe barrel. Before doing so, however, it is desirable to lessen thetension of spring 3| so that the tools will have no tendency to pullaway the strip from the barrel in the backing-off operation.

It has been found in practice that the strip has a tendency to heel overwhen it is first drawn between the tools; and that this can readily becorrected by a repetition of the operation. In order to simplify therepeat step, it is preferred that, when the tendency to heel firstappears, the strip be caused to turn away from the direction of movementof the tools, so that its convolutions will lie in the positions shownin Fig. 13. If this is done, then upon completion of the rundown of thetools in the direction indicated by the arrow (Fig. 13), and after thetrailing end of the strip has been secured to the barrel by clamp it, itis only necessary to reverse the machine to cause the strip to be drawnin the opposite direction. In this runback over the barrel the ironingtools will lift each convolution without interference from the nextadjacent one, and without any change in adjustment will complete thedrawing operation and cause the strip to assume a substantiallyperpendicular position on the surface of the barrel. Under thesecircumstances the drawing operation will be completed at the end of therunback and the tools may then be withdrawn after first loosening thespring 3i, as heretofore mentioned.

It has also been noted, particularly with barrels of larger sizes, thatthe strip does not assume a position tangent tothe suriace:.l5immediately opposite the ironing tools, but first touches the barrel ata point some two or three inches behind the tools, as is shown in Fig.14. If this condition tends to cause any inaccuracy in the locating andproper spacing of the convolutions of the fin, the defect may readily becorrected by engaging the strip between the surfaces of a pair ofguide-rolls mounted on the end of an arm 16 which is pivoted at 11 to anupright E8. The upright is secured to the traveling carriage of themachine so that it will advance the guiderolls along the barrel atprecisely the same rate as are the tools 25, 26; and the rolls 15 arepreferably urged toward each other by a spring 19 (Fig. 15) so that theymay engage the strip tightly enough to lay it on the barrel at preciselythe desired rate, thereby to assure proper spacing between theconvolutions. In the illustrated structure the arm 16 is urged away fromthe barrel by a spring 80 so that the rolls are normally held in anout-of-contaot position. When it is desired to guide the strip in themanner just described, the arm is lowered by an appropriate movement ofa lever 8| having a cam portion 82 which is adapted to engage the armand press it downwardly.

Upon the completion of the drawing-out step the helical fin l6, held inits tightened condition upon the barrel by the engagement of its ends inthe two clamping rings, is ready to be bonded to the surface I5. Wherethe fin is made of copper, as in the assumed case, it has been foundthat a low melting point silver solder will serve adequately to secureit to the barrel and at the same time to form a perfect thermal bondtherewith. In the preferred method, after first cleaning'and fiuxingboth the barrel and the fin, a strip of solder wire 46 of appropriatecharacter is hooked under the leading end of the fin within a notchwhich has been provided for that pur pose, and the barrel is againrotated whereby to Wind the wire between the convolutions of the fin.During this operation a hand tool may be inserted between the fins andis pressed against the wire whereby to cause that element tightly to hugthe surface l5. At the completion. of the winding operation the tail endof the wire may be hooked under the trailing end of the fin within asuitable notch if desired.

It will be recognized'that when the barrel and fin are subsequentlyheated, the copper of the latter will expand to a considerably greaterex tent than will the steel of the former, and that this differentialexpansion will loosen the fin. It is desirable, therefore, to apply somemeans to the fin at this time which will hold its convolutions in thedesired spaced'relationsh-ip during the period of looseness. One suchmeans may consist of a cord of asbestos or glass fibre, which is of suchsize that when wound around the barrel it will fill the space betweenadjacent convolutions of the fin, wherefore to hold them in place.Another suitable means comprises a series of combs 83 applied to thefins at spaced points, with their teeth 84 engaging the convolutions tohold them in place, as is shown in Figs. 16 and 17. 'In still anotherinstance a quick-setting cement was smeared over the fins, and thisserved adequately.

The barrel, fin, etc. are now ready to be heated for the purpose offusing the solder wire. This operation may be performed in an inductionfurnace, or in any other suitable way. When an induction furnace isemployed, it is of importance that the clamping rings and shall beasth-in as possible in order that the current needed for their heatingmay not be so high as to cause an overheating of the barrel.

It has been noted above that in the heatin operation the copper fin willexpand to a greater extent than will the steel barrel. This is of someadvantage in that it permits the molten solder to flow under the fin andestablish a perfect bond between its inner edge and the surface of thebarrel. Insofar as the differential heating tends to loosen the fin, anybad effect is completely offset by the presence of the holding meanswhich were described above. After the cylinder and fin have been cooled,and the solder has thoroughly set, the combs .83 or other holdin meansmay be stripped away. The results of the bonding operation may be seenin Fig. 5.

It will be recalled that the method includes a final step the purpose ofwhich is to straighten the strip and simultaneously to harden it wherethat is required. The copper strip of the illustrative case requiresboth, for at the completion of the bonding step it is usually bad-1ywarped and is in almost dead-soft condition. As a preliminary to thisstep the barrel is again set up on the stub arbor 2| of the machine ofFig. 4, with its driving flange 35 engaged by the driving pin 34 of theface plate; the leading end of the strip is again engaged between thefaces of the ironing tools 25 and 26; and the guide-rolls which take nopart in the hardening step are moved out of the way. The exact pressurewhich should be applied to the strip by tools 25 and .26, and spring 3],at this time will again depend .upon the size and character of thestrip, and upon the extent of the work which is to be performed in thisfinal step .of the method. If, for example, straightening alone isrequired, then the tools need do no more than iron the strip, the spring3| being adjusted accordingly. straightening and hardening are required,as in the assumed case, then the spring must be ad justed to such apoint that the tools actually deform the metal of the strip.

The preliminary set-up of the barrel, strip and .tools .in the machinehaving been completed, that machine may again be started. Obviously,rotation of the barrel around its own axis again results in the drawingof the strip between the faces of the ironing tools, therebyfiattening'and straightening it. Simultaneously, of course, the metal ofthe strip is progressively squeezed and cold-worked from one end to theother to such an extent as to work-harden it. After the entire strip hasbeen ironed in this way, the machine may be stopped, the tools backedofl, and

I the barrel l2 removed from the stub arbor. The

driving ring 20 may be removed, as may also the clamp 40, and the twoends of the helical fin may now be cut away. It is preferred, however,that they be retained in the clamps during the straightening andhardening step, so as to assure that the strip will not be pulled awayfrom the barrel during this last-mentioned operation. When thisstraightening and hardening step has been completed, and the ends of thestrip have been cut away, the entire finning operation is complete; andthe barrel may be subjected to whatever treatment is required before itis incorporated as a part of a finished engine.

In carrying out the straightening and hardening step of the method, theironing tools 25 and 26 may be advanced along the barrel by theautomatic feed screw of the machine, just as they were advanced duringthe earlier applying and tightening step. It is preferred, however, thatWhere both they be driven by the strip itself during this operation, sothat they may follow precisely the lead of the strip. This may be doneby releasing the carriage of the machine, and the frame 21 which itcarries, from the automatic feed screw 36 through any usual clutchdevice (not shown). Under such circumstances the tools, squeezing thestrip between them, must follow the lead of that strip when the barrelis rotated, thereby advancing themselves, frame 21, and the carriage.

It is further preferred, however, that the fin be relieved of the loadof driving the carriage and other heavy parts. Thus in the machine ofFigs. 4 and 8 it will be noted that the tools 25, 26 are mounted in aU-shaped block 50, which has a pair of trunnions and 52 journaled in theforward ends of the arms 53 and 54 of the forked frame 21 so that theblock, and the tools which it carries, may have some limited slidingmovement in the frame 21 under certain circumstances hereinafter to beconsidered. It will also be noted that the block 50 is provided with anarm 55 having a roller bearing 56 on its outer end which rides on theframe 21 to prevent rotation of the block in a counterclockwisedirection; and that a stop element 51 has been provided to preventrotation in the opposite direction.

In setting up the machine to perform the drawing-out step of the method,the block 50 is moved to the position shown in Fig. 4, with its leftedge abutting against the arm 53 of the frame 21; and suificient tensionis applied to sprin 58 by an adjustment of nuts '59 on the stud portion60 of trunnion 5!, to hold the block in this established position. Withthis set-up, frame 21 and block 58 are to all intents and purposes asingle unit which can be advanced by feed screw 36 at a desired rate,consequently advancing the tools and performing the locating anddrawing-out step of the method in the manner which has heretofore been:described.

Where the machine of Figure 4, is to be employed for carrying out thestraightening and hardening step of the method, it is set up in aslightly different way from that just described. Thus, the tension ofspring 58 is relieved by unscrewing nuts 59, the frame 21 is disengagedfrom the feed screw 36 and is backed up to such an extent that block 5!]lies substantially midway between arms 53 and 54; and the feed screw 36is then re-engaged with the frame through the usual clutch device. It isevident that with this set-up, the frame 21 is adapted to be advancedlengthwise of the barrel by the feed screw 36 in precisely the same waythat it was during the earlier fin-applying step. The block 5|] andtools 25, 26 are, however, free to float on trunnions BI, 52, betweenarms 53 and 54 on the frame 21. These parts are, therefore, advancedalong the barrel entirely by the engagement of the tools with thehelical strip. In the event that the fin has been retained in theposition originally established, the tools will be moved along thebarrel in perfect unison with the frame 21. If, however, there has beena slight shifting of the positions of the convolutions of the fin,during the bonding step for example, then the tools will move block 53in frame 21 so that they may follow precisely the lead of the fin duringthe hardening step. With this arrangement it is evident that the toolsare always driven by the fin during the hardening and straighteningstep, and yet that fin is completely relieved of the load of.drivingthe.

frame 21, the carriage, and other heavy parts of the machine.

The ironing of the strip during both the drawing-out step and thestraightening and hardening one, places a very heavy load upon the tools25 and 26 in a vertical direction. In order that this load may not beconcentrated upon pivot pin 30 for the swinging tool 25, a member 63(see Fig. 9) is secured to the forward end of the block 50 with its arm64 overlying the tools 25 and 26 so as to support them. It is evident,however, that vertical support may be provided for the arms in any otherconvenient and satisfactory way.

The machine is also provided with a quickopening device 61 whichfacilitates the application of tension to spring 3! when the tools areengaged with the strip at the start of any drawingout or straighteningoperation, and to relieve the tension of that spring at the completionof that operation. This device may be constructed in any desired way. Ashere shown, it comprises a pair of collars 68 and 69 (Figs. 4, 10 and11), of which the collar 68 is mounted to rotate upon a stub shaft 10carried by the swinging arm 29, whereas collar 69 is keyed at 11 to theshaft so that it may not rotate but have some limited axial movementthereon. The two opposing faces 12 of the collars are cams, whereforerotation of collar 68 through a quarter turn will move collar 69outwardly to compress spring 3| or inwardly to relieve the tension ofthe spring, depending, of course, upon the direction of rotation. Whenthe collars are in the position shown in full lines in Fig. 4, thetension of spring M is verylight, or perhaps non-existent, and hence thetools 25 and 26 may readily be engaged with the leading end of strip It.When that has been done, the collar 68 may be given a quarter turn inclockwise direction by its integral handle 13, thereby moving collar 69to the right to compress spring 3| and apply its tension to the swingingarm. The machine may then be operated to carry out either thedrawing-out step or the hardening one. At the completion of thatoperation, whatever its character, the collar 68 may be given a quarterturn in a counterclockwise direction to relieve the tension of spring3|, and allow the tools to be Withdrawn from the strip with a minimum ofefiort. With this arrangement it will be apparent that screw 32 andlock-nut 33 need be used only for an initial adjustment of the tensionof spring 3| to a desired value for the particular operation to beperformed. If, for example, a series of identical fins are to be drawnout on the surfaces l5 of a series of barrels of the same size, thetension of spring 3| may be adjusted by screw 32 at the start of thedrawing-out operation on the first of the cylinders, and that adjustmentwill serve for the entire group. Likewise, if a group of barrels are tohave their fins straightened and hardened, a single adjustment of thescrew for the first of the barrels is all that is required.

The machine which is illustrated in the drawings is intended for more orless universal use, and the stub 2| and face plate 22 are threaded tothe mandrel (see Fig. 4) so that they may readily be removed and anotherarbor and face plate substituted to receive a barrel of difierent sizefrom the one shown. Of equal importance, the ironing tools 25 and 26 areso designed and arranged that they may be employed to carry out eitherthe drawing step, or the ironing-straightening step of the method, uponfins of different widths and thicknesses. Thus it will be observed thattheinnerfacesof, these members are substantially flat; and that thepivot pin 30 about which tool 25 swings has its bearing surface '14(Fig. 12) formed eccentrically to the portion 85 at its lower end bywhich the pin is secured to block 50. With this arrangement any rotationof the pin 39 about its seat 86 in the block will move the rear end oftool 25 closer to or farther away from the rear end of tool 26. Thus thetools may be set with their faces at such an angle as to produce athinning of the outer edge of the strip during a drawing-out operation,for example; or they may be set substantially parallel to one anotherfor the performance of a straight ening-ironing step. Likewise, ofcourse, the positions of the tools may be adjusted to accommodate finsof greater or lesser thickness or various widths.

1n the foregoing the method and apparatus have been described withparticular reference to the application of a copper fin to a steel body.The method is not, however, so limited in its character. It may be usedfor applying a fin of any desired material. If, for example, steel finsare preferred, they may be applied to the illustrated cylinder barrel bythe method much more readily and economically than by any presentlyknown practice. Thus, a strip of comparatively soft steel may be reducedto helical form so that it may be fitted over the barrel, and itsconvolutions may be located and drawn out in exactly the same way as wasthe copper fin which has already been described. That steel strip may Ithen be bonded to the cylinder by soldering, or if more strength isrequired, by a brazing or welding operation. Finally, the strip may bemechanically worked to straighten it, and to harden it if that isrequired, exactly as heretofore described in connection with the copperstrip.

It is likewise evident that my method is not limited to use in applyingheat radiating fins to cylinders of internal combustion engines, or infact to a body having the ends of its cylindrical surfaces bounded byenlarged flanges or shoulders. On the contrary, it is readily applicableto the firming of conventional tubing or other body, and the machine ofthe present invention may be used for carrying out the several steps ofthe method in such an application in exactly the way which has beendescribed herein.

Having described my invention, what I claim as new and useful is:

1. In a machine of the character described, a supporting block, a pairof ironing tools having opposing faces for engaging a strip disposedbetween them, one of said tools being secured in stationary relation tosaid block and the other being adapted to move towards and away from thestationary one, a projection on said block, a spring disposed betweensaid projection and the movable one of said tools to urge it towards thestationary one, an adjusting screw for varying the tension of saidspring and a quick-opening device between said spring and the movableone of said tools, said quick-opening device comprising a stub shaftmounted on said movable tool,

a pair of collars mounted on said shaft with the outer collar engagingan end of said spring, and a key for preventing rotation of saidlast-mentioned collar while permitting it to slide along said shaft,said collars having opposing cam faces whereby rotation of the inner onewill move the outer one to increase the tension of said spring.

2. In a machine of the character described, a supporting block, a pairof ironing tools having substantially fiat opposing faces for engaging astrip disposed between them, means for securing one of said tools infixed relation to said supporting block, a pivot pin for supporting therear end of the other of said tools, and spring means for urging thelatter tool towards the stationary one, said pivot pin beingeccentrically mounted in said block whereby it may be rotated to movethe rear end of the pivoted tool towards and away from the rear end ofthe stationary one.

3. In a machine of the character described, an arbor, means for rotatingsaid arbor about its own axis, a frame mounted alongside of said arbor,a supporting block having trunnions journaled in said frame, said blockand trunnions being adapted to slide in said frame in a directionparallel to the axis of said arbor, a pair of ironing tools having theiropposing faces adapted to engage the opposite sides of a strip carriedon said arbor, spring means for urging said ironing tools towards eachother, and other spring means releasably holding said block againstsliding movement in said frame.

4. In a machine according to claim 3. characterized by a stud secured toone of said trun- REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Number Name Date 715,180 Trowe Dec. 2, 19021,107,005 White Aug. 11, 1914 1,151,721 Sahlin Aug. 31, 1915 1,404,122Hofuring Jan. 17, 1922 1,639,912 Whittinghain May 31, 1927 1,909,704Morseth May 16, 1933 1,992,297 Dewald Feb. 26, 1935 2,004,387 DewaldJune 11, 1935 2,041,461 Floyd et a1. May 19, 1936 2,087,723 McCord July20, 1937 2,151,685 Berg Mar. 28, 1939 FOREIGN PATENTS Number CountryDate 423,356 Germany Dec. 29, 1925

